If it's in your lymph nodes that just means they've discovered that the cancer has spread to that point from the breast. It doesn't mean it's gone any further. I imagine they will check with some more scans. I know it's awful, the whole thing is a shitfest, but try not to cross any bridges until you come to them. As @SoldierCrab says, it'll probably alter the length and type of chemo you're on, but know that you're in one of the best places in the world to have this disease and your medical team will take very good care of you. You are going to feel such love from friends and family, you're going to deepen your knowledge of yourself, and you'll even have some crazy laughs along the way, especially if you keep hanging out here! We'll hold your hand every step of the way.
Give your GP, or breastcare nurse or your surgeon a call if you have a burning question that's keeping you up, and take a big list of all your other questions to your next appointment. Waiting and wondering is the pits so never hesitate to shorten the torture for yourself by firing off an email! The best advocate for your breast cancer is you. If you struggle to ask the questions and get the answer, bring a friend or family member with you.
Hang in there @Susie9. Take some deep breaths and focus on just one hour at a time. Big hug, Kate xox